EXCEED THE SPACE PROVIDED. "^ This proposal is submitted by The Biostatistics Center of The George Washington University to serve as the Operations Coordinating Center for TrialNet in response to RFA DK-01-004 "Type 1 Diabetes TrialNet: Core Support Facilities." The functions of the Operations CoordinatingCenter (OCC) for TrialNet are to provide for thecontinuation of the ongoing DPT-1 parenteral and oral insulin primary prevention trials and to support future studies with the ultimate objective of prevention of type 1diabetes and its amelioration. As of 1997 it is estimated that worldwide about 124 million individuals had diabetes mellitus, of which 3.5 million have type 1 diabetes, the majority of these having an onset during childhood. In the US alone,approximately 15.7 million individuals, or 5.9% of the total population have diabetes, with at least 500,000 or 0.12% of the US population, 1.2 per 1000 population, then having type 1 diabetesmellitus. The onset of type 1 diabetes mellitus is one step in a chain of events that begins at the moment of conception. Genetic polymorphisms,principallyHLA haplotypes, have been identified that confer an increased risk of developing diabetes, or are protective.Genetic defects render an individual susceptible to an aberrant immunologicresponse to one of possibly many environmental insults. Following the environmental trigger, the T-cells begin an assault on the insulin- producing beta or islet cells of the pancreas. This autoimmuneresponse is manifest by the appearance of antibodies and the subsequent loss of first phase insulin response. Thereafter beta cell function declines. This makes it feasible to conduct studies of the genetics of type 1 diabetes and immune tolerance, the role of environmental pathogens, the characterization of autoimmunity and immune tolerance, evaluation of the risk of developing diabetes, and various interventions aimed at immune tolerance or preservation of beta cell function. The objective of The George Washington University Biostatistics Center is to apply our considerable resources and experience to the completion of the following main tasks to ensure the clinical and scientific success of the multifaceted studies to be undertaken and completed by TrialNet. (1) Study Coordination and Planning: We will help establish an efficient organizational structure to ensure that all activities advance in a coordinated fashion. (2) Data Management Activities: We will apply our established systems for on-going data collection and data management, and will generate periodic reports summarizing the execution of the trial. (3) Statistical Analysis: We will provide statistical leadership in the design of studies, and perform interim and final analyses in an expeditious and timely manner. (4) Documentation: We will provide for the orderly closeout of all studies with complete documentation and dissemination of relevant materials to the NIH and the public.